Tension control for traveling strip material



April 13, 1954 G. P. MQGRAW, JR

TENSION CONTROL FOR TRAVELING STRIP MATERIAL 1951 Filed Sept. 24

2 Sheets-Sheet l //V l/E N701? R Ma 61% MM ATTO/M/f) Ap 1954 G. P.MCGRAW, JR

TENSION CONTROL FOR TRAVELING STRIP MATERIAL Filed Sept. 24, 1951 2Sheets-Sheet 2 nv VE/VZ'OR 6. PMc GRA MM 5r Patented Apr. 13, 1954TENSION CONTROL FOR TRAVELING STRIP MATERIAL George P. McGraw, Jr.,Downers Grove, Ill., assignor to Western Electric Company, Incorporated,New York, N. Y.

York

, a corporation of New Application September 24, 1951, Serial No.248,026

11 Claims. 1

This invention relates to a tension control device and more particularlyto a device for controlling the tension to strips of metallized paper asthey are wound into electrical condensers.

In the art of winding condensers or the like from strip material, it isdesirable to control the tension of the strips of material as they arebeing wound. Where the condensers are wound from supply rolls of thestrip material in which the rolls are large and have considerableinertia, the frequent starting and stopping of the strip material duringthe winding of the condensers presents some difiiculties and rendersdifficult the control of the tension of the strips as they are beingwound.

It is an object of the present invention to provide an improvedmechanism for controlling the tension of travelling strip material.

In accordance with one embodiment of the invention as applied to acondenser winding machine, a shaft is provided for supporting a supplyroll of the strip material, which shaft is driven from a motor through aslip clutch to drive the supply roll. As the strip is being wound, aloop is formed therein by a dancer roller to which springs are connectedfor urging the roller for movement in a predetermined straight path toapply a tension to the strip. A variable braking pressure is applied toa brake disc on the shaft by a movable brake shoe actuated by compressedair from a supply line having a uniform air pressure and a control valvewhich is connected in the supply line and has a bleed aperture thereinthrough which air escapes. A needle valve connected to the dancer rollerfor movement therewith varies the size of the bleed aperture and theamount of air bled from the supply line to control the pressure appliedto the brake and the braking action on the supply roll. Thus, themovable biased dancer roller and the brake mechanism controlled by thedancer roller through the bleed valve cooperate to obtain a balancedcondition to maintain a substantially uniform tension in the strip. Toapply a controlled variable tension to the strip, the ends of thesprings connected to the dancer roller may be connected to a mechanismfor advancing or retracting the springs under control of a cam driven intimed relation to the winding of the condenser.

Other objects of the invention will become apparent by reference to thefollowing detailed description thereof when considered in conjunctionwith the accompanying drawings illustrating diagrammatically apreierredembodiment thereof, in which Fig. l is a. diagrammatic side elevation ofa winding machine with the improved tensioning device applied thereto;

Fig. 2 is an enlarged plan sectional view of a portion of the windingand tensioning device;

Fig. 3 is an enlarged detailed view of the brake structure for retardingthe rotation of the supply roll;

Fig. 4 is an enlarged detailed view of the needle valve for controllingthe escape of air from the compressed air line; and

Fig. 5 is a detailed vertical sectional view showing the mechanism formounting and guiding the dancer roller for movement.

Referring to the drawings the reference numeral It indicates a windingarbor of a condenser winding machine onto which a pair of composite websor strips I2 of metallized dielectric are wound to form the condenser I3. The composite webs I2, which may be of various types, are formed froman elongated strip of paper dielectrio onto one side of which acontinuous film of vaporized metal has been deposited. Unwound fromsupply rolls !5, the webs I2 pass around guide rollers I6, I7, and I8and dancer rollers I 9, which latter are rotatably mounted on shafts 20.Each of the shafts 20 has connected thereto at opposite ends of theroller I9 one end of a pair of tension springs 2|, the opposite ends ofwhich are connected to a bar 22. The springs serve to stress the dancerrollers I9 for movement outwardly to maintain the webs I2 under tension.A loop 23 is formed in each of the webs I2 as it passes between theguide rollers I6 and I7 and around the dancer roller I9. The rollers I8may be controlled to serve as pinch rollers to grip the webs I2 duringthe cutting thereof by knives 24 upon completion of the windingoperation to prevent the ends of the webs I2 to be pulled back by theaction of the biased dancer rollers I9.

Each of the supply rolls I5 is mounted on a supporting shaft or rod 25which is removably and rotatably mounted in a movable bearing 26. At itsother end the shaft fits into a socket member 28 on a shaft 29 and isremovably connected thereto for rotation with the shaft. The shaft 29,which is rotatably supported in bearing supports 30, is driven through aslip clutch 32 and a speed reducing unit 33 from a motor 34. The slipclutch 32 applies a continuous torque to the shaft 29, which torque issufilcient to drive the supply roll of paper at a lineal speed of theweb greater than that at which it is wound on the arbor. However, theeffective torque applied by the shaft 29 to the roll of paper I5 iscontrolled by a device for applying a variable braking or retardingforce to the shaft 29.

A brake disk or drum 38 is fixed to the shaft 29 intermediate its endsand is rotatable between a fixed brake shoe 3% and a movable brake shoeM. The brake disk 38 may be faced with brake lining 4| on opposite facesthereof if desired. The movable brake shoe 4% is actuated by anysuitable actuating device 43 which is operated by air pressure. Theactuating: device 43 illustrated herein comprises a hollow cylinder liover the open end of which is secured a flexible diaphragm 45 to whichthe movable shoe Ml is attached. The cylinder M is supported againstmovement and is connected to a supply line 45, which in turn isconnected to a source of compressed air. The air in the supply line 46is under a predetermined constant pressure, controlled by a pressureregulating valve 41 and the pressure thereof may be indicated by a gage43 connected to the line 46.

Means are provided to vary the amount of air supplied to the actuator 43to vary the braking pressure applied to the brake disk 3% and tocooperate with the action of the dancer roller I9 to control the tensionof the webs I2 during the winding of the condenser. For this purpose apressure control valve 59 in the form of a bleed valve is connected intothe air supply line 36 to allow a portion of the air to escape from theline. The valve has a pair of diametrically opposed bleed apertures 5|therein, and a control element in the form of an elongated tapering rodor needle 53 is disposed within the apertures El and is movable thereinto vary the size of the bleed orifices of the valve 50 to vary theamount of air escaping from the valve 55 and the supply line 46.

' The tapered element or needle 53 is fixed to a ring 54 which isrotatably connected through a ball bearing 55 to the shaft 2!! of thedancer roller IE. Anti-friction bearing rollers 58 (Fig. 5) mounted oneach end of the shaft of the dancer roller I9 ride between pairs ofhorizontally disposed rails 59-58 for guiding the dancer roller formovement in a straight path and a pair of gears I50 fixed to the shaft20 on opposite ends of the dancer roller I9 mesh with racks SI mountedparallel to the tracks 59 to impart parallel move ment to the dancerroller I9 as it is carried back and forth between the pull of the web I2and the springs 2I.

It will be understood that there are two separate tension controllingunits, one for each supply roll and web therefrom, which units aresubstantially identical in operation and in structure.

Mechanism is provided to supplement the above-described mechanism forapplying a predetermined variable tension to the webs as they are beingwound onto the arbor. In the embodiment disclosed herein each of thebars 22 intermediate its ends has connected thereto a cable 65 which iswound around a drum 66 mounted on a shaft 61 which is supported forrotation in suitable bearing brackets 68. A cam lever 69 secured to theshafts 81 has a cam follower I6 thereon which engages a cam II fixed toa cam shaft I2 suitably supported for rotation in the bearing brackets68. The cam shafts F2 are suitably'connected as by means of a sprocketand chain drive to a transmission unit 56 which is capable of beingconnected to the condenser winding machine for actuation in timedrelation to the rotation of the winding arbor II! and may be connectedand disconnected as desired by manual actuation of a control lever (notshown) The above-described tensioning device is capable of applying asubstantially uniform tension to the webs I2 as they are wound onto thearbor or of applying a predetermined variable tension to the variousportions of the webs as they are being wound. When it is desired toapply a uniform tension to the webs I2 during the winding of thecondenser, the transmission I6 is disconnected from the condenserwinding machine and the bars 22, to which the springs 2I are secured,remain stationary. The springs 2 I, which are relatively long, will thusapply a substantially uniform tension to the dancer rollers I9, tendingto move the dancer rollers I9 outwardly away from the guide rolls It andIT. The pressure of the braking device &3, tending to govern therotation of the shafts 29 and 25 and the feedin of the webs I2 from thesupply rolls I5, cooperates with the action of the springsZI to maintainthe webs I2 under predetermined tension. With the tapered controlelement 53 of the valve 59 mounted for movement with the dancer rollerI9 to vary the amount of air escaping from the air line 46 and thuscontrol the braking pressure applied to the supply rolls I5, a balancedcondition is achieved between the retarding or braking force applied tothe supply roll and the pull of the dancer rollers IS on the loops 23 ofthe webs I2 to maintain a substantially uniform tension on the webs.

Any increase in the tension on the webs I2 will result in the inwardmovement of the dancer rollers I9 and a corresponding movement of thetapering control element 53 resulting in the escape of more air from thebleed valve 5i), thereby lessening the air pressure applied to thebraking device 43' and lessening the retarding effect thereof on therotation of the supply rolls I5 and the decreasing of the tension on theweb I2 to a predetermined value. Conversely, any decrease in tension inthe webs I2 during the winding of the webs results in the outwardmovement of the dancer rollers I9 and a corresponding movement of thetapered control elment 53 resultin in the reduction of the bleedapertures 5I and a consequent increase in pressure on the braking device43, which results in a corresponding increased retarding effect on therotation of the shaft 29 and the supply rolls I5, thus increasing thetension of the webs E2 to the predetermined value to which the tensiondevice is set. The tension applied to the webs I2 may be varied to apredetermined value by adjusting the pressure regulating valve 41 tovary the air pressure in the supply line 66.

The device is capable of applying a predetermined variable tension tothe Webs I2 during the winding of the webs into a condenser. Toaccomplish this the transmission I6 is connected to the winding machineto cause the rotation of the shafts I2 and the cams I I, which actuatesthe drums 66 and the bars 22 in timed relation to the winding of thewebs to vary the stress of the springs 2I on the dancer roliers I9 andthus vary the tension in the webs I2 as they are being wound. The camsII are removably secured on the shaft i2 and may be replaced by othersof various designs and contours to effect the desired movement of thedrums 66 and obtain the desired predetermined variable tension of thewebs I2 during the winding of the webs.

It is to be understoodthat the above-describedarrangements are simplyillustrative of the application of the principles of this invention.Numer ous other arrangements may be readily devised by those skilled inthe art which Will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

1. A tension control device for travelling material comprising means forsupporting a wound supply of material, means for withdrawing materialfrom said supply, means for rotating said wound supply of material tounwind said material, variable brake means for retarding the rotation ofsaid supply of material, and means for varying the effectivebrakingforce of said brake means including means engaging the materialintermediate the supply and the withdrawing means and movable inresponse to variations in tension of said material, means connecting asource of compressed air under a uniform pressure to the brake means forconducting the compressed air to said brake means to actuate the brakemeans, and means in said connecting means for bleeding off a portion ofthe air being fed to the brake to vary the pressure of the air to saidbrake means in accordance with movements of the material engaging means.

2. A device for tensioning a strip of material as the strip is beingWound onto an arbor comprising a shaft for supporting a roll of stripmaterial, drive means including a yieldable connection for rotating saidshaft to unwind the strip from the roll, guide rollers including amovable dancer roller for forming a loop in said strip as it advancestoward said arbor and for tensioning said strip, spring means stressingsaid dancer roller for movement in a predetermined path to increase thesize of the loop of the strip and apply a tension thereto, a brakecomprising a brake member on said shaft and a brake shoe engageable withsaid member, a pneumatic device for actuating said brake shoe, conduitmeans connectible to a supply of compressed air at a predeterminedconstant pressure for supplying said compressed air to said pneumaticdevice for urging said shoe against said brake member to retard therotation of said shaft, valve means venting a portion of said compressedair from said conduit means, and means movable with said dancer rollerfor controlling said valve to vary the amount of air vented thereby tovary the braking pressure of the shoe on said drum.

3. A tension control device for travelling strip material-comprisingmeans for advancing said strip, means including a shaft for supporting aroll of stripmaterial, drive means for rotating said shaft to unwindsaid roll, guide means including a movable dancer roller for guidingsaid strip through a predetermined path and forming a loop in saidstrip, spring means stressing said dancer roller for movement in onedirection tending to increase the size of the loop of the strip andapply tension to said strip, fluid actuated brake means connectible to asupply of fluid under a predetermined uniform pressure for applying abraking force to said shaft to retard the unwinding of said supply roll,and a valve communicating with said fluid operated brake means forreleasing some of the fluid therefrom, said valve having a controlelement movable with said dancer roller for varying the amount of fluidreleased to effect a variation in the braking pressure applied to saidshaft in response to variations in position of said dancer roller.

4. A strip tensioning device for use in a strip processing apparatushaving means for advancing said strip, said tensioning device comprisingmeans including a shaft for supporting a supply roll of strip material,drive means including a a portion of said strip transversely to the pathof travel thereof and to apply tension to said strip, fluid actuatedbrake means connectible to a. supply of fluid under a predetermineduniform pressure for applying a braking force to said shaft to retardthe unwinding of said supply roll, a valve communicating with said fluidoperated tively long tapering control element disposed in said orificefor movement with said dancer roller for varying the size of the orificeand the amount of fluid released to effect a variation in the brakingpressure applied to said shaft in response to variations inposition ofsaid dancer roller.

5. A strip tension device for travelling strip material comprising meansfor advancing said strip, means including a shaft for supporting a rollof strip material, drive means including a yieldable connection forrotating said shaft to unwind the strip from said roll, guide meansincluding a movable dancer roller for guiding said strip through apredetermined path and forming a loop in said strip, spring meansstressing said dancer roller for movement in one direction tending toincrease the size of the loop of the strip and apply tension to saidstrip, fluid actuated brake means connectible to a supply of fluid undera predetermined uniform pressure for applying a braking force to saidshaft to retard the unwinding of said supply roll, a valve communicatingwith said fluid operated brake means for releasing some of the fluidtherefrom, said valve having a control element movable with said dancerroller for varying the amount of fluid released to effect a variation inthe braking pressure applied to said shaft in response to variations inposition of said dancer roller, and cam controlled means operable intimed relation to the means for advancing a strip to vary the stress ofsaid spring means on said dancer roller for etifecting a controlledvariation in tension in the s rip.

6. A tension control device for travelling strip material comprisingmeans for advancing said strip, means including a shaft for supporting aroll of strip material, drive means including a slip clutch for rotatingsaid shaft to unwind the strip from said roll, guide means including amovable dancer roller for guiding said strip through a predeterminedpath and forming a loop in said strip, means including a pair of springshaving one end of each thereof connected to said dancer roller forstressing said dancer roller for movement in one direction tending toincrease the size of the loop of the strip and apply tension to saidstrip, a movable supporting member connected to the other ends of saidsprings, a. cam rotatable in timed relation to said means for advancingsaid strip, means actuated by said cam for moving said support to varythe stress of said springs on said dancer roller for effecting a,controlled variation in tension in the strip, fluid actuated brake meansconnectible to a supply of fluid under a predetermined uniform pressurefor applying a braking force to said shaft to retard the unwinding ofsaid. supply roll, a valve communicating with said fluid operated brakemeans having an orifice for releasing some of the fluid therefro and arelatively long "tapering control element disposed in said orifice,

released to efiect avariationin the, braking .pressure applied to saidshaft in response to variations in position of said dancer roller '7'. Adevice for tensioning a strip of material as the strip is being woundonto an arbor comprising a shaft for-supporting a roll of stripmaterial, means for rotating said shaft to unwind the strip from theroll, guide rollers including a movable dancing roller for forming aloopin said strip as it advances toward said arbor and for tensioning saidstrip, spring means for stressing said dancing roller for movement in apredetermined path to increase the size or" the loop of the strip andapply a tension thereto, cam controlled means operable in timed relationto the rotation of said arbor for varying the stress of said springmeans onsaid dancer roller and the tension applied thereby to saidstrip, a brake comprising a brake member on said shaft and a brakeshoeengageable with the member, a pneumatic actuator for said shoe,conduit means connectible to a supply of aircompressed to apredetermined. constant pressure and to said actuator for urging said:shoe against said drum to retard the rotation of said shaft, valvemeans for bleeding a portion of said'compressed air from said actuator,and means movable with said dancing roller for controlling said valve tovary the amount of air escaping therefrom and the braking pressure ofthe shoe on said drum.

8. A tension control device, for travelling strip material comprisingmeans for advancing said strip,'a shaft for supporting a roll of stripmaterial, drive 'means including a slip clutch for rotating said shaftto unwind the strip from said roll, guide'rollers including a movabledancer,

roller for forming a loop in said strip as it advances, spring meansstressing said dancer roller for movement in a predetermined path toincrease the size of the loop of the strip and apply tension thereto, anair-operated braking device for applying a braking force to said shaftto retard the unwinding of said roller, means connectible to a supply ofair under a predetermined uniform pressure for supplying said air tosaid braking device, a valve for venting some of the air supplied tosaid braking device, said valve having a control element for varying theamount of air vented from said valve, and means connecting said controlelement for movement with said dancer roller to effect a variationin-the braking pressure applied to said shaft in response to variationsin position 'of saiddancer roller.

9. A tension control device for travelling strand or strip materialcomprising means for advancingsaid strip, meansincluding ashaft forsupporting a roll of strip material, drive "means including a slipcIutchif r rotating;said,-shaft ,to

unwind the strip from a roll, guide rollers including a movable dancerroller for forming a loop in said strip as it advances, spring meansstressing said dancer roller for movement in a predetermined path toincrease the size of the loop of the strip and apply tension thereto, an

air-operated braking device for applying a braking force to said shaftto retard the unwindingof said roll, means connectible to a supply .ofcompressed air at a predetermined uniform pressure for supplying saidair to the braking device, a valve for venting some of the air suppliedtosaid braking device, said valve having a control element for varyingthe amount of ,air vented from said valve, means-connectingsaid controlelement to said dancer roller for movement therewith .to effect avariation in the braking pressure applied to said shaft in response tovariations in position of said dancer roller, and means operable intimed relation to the means for advancing said strip to vary the stressof said spring means on said dancer roller for eifecting a controlledvariation in tension in the strip.

10. A tension control device for travelling strip material comprisingmeans for advancing said strip, a shaft for supporting .a roll of stripmaterial, drive means including a y-ieldable element for rotating saidshaft to unwind the strip from a roll, guide rollers including a movabledancer roller for moving a ,portion of said strip transversely of itspath of travehspring means stressing said dancer roll for movement in apredetermined path to increase the transverse movement of said portionof the strip and apply tension to the strip, air-operated brake meansconnectible to a supply of compressed vair at a predetermined uniformpressure for applying a braking force to said shaft to retard theunwinding of said roller, a valve for venting some of the air suppliedto said brake means, said valve having a control element for varying theamount of air vented from said valve, and means connecting said controlelement for movement with said dancer roller toeffect a variation in thebraking pressure applied to said shaft in response to variations inposition .of said dancer roller.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,082,633 Johnstone June 1, 1937 2,199,603 Ackley May '7, 19402,430,022 Lambach Novr i, 1947 2,460,694 Haswell Feb. 1, 1949 2,462,558Scheuermannet a1. Feb. 22, 1949 FOREIGN PATENTS Number Country Date787,357 France July 1, 1935

